In parts assembly lines, for example, there are cases in which workpieces (workpieces in process) are stored between two adjacent processes of a workpiece conveyance path. In such cases, storage conveyors are generally used. Conventionally, in such assembly lines, workpieces are arranged in a line on a storage conveyer in a workpiece conveyance direction, and therefore, the storage conveyor is elongated depending on the number of stored workpieces. When a large number of workpieces are stored, the size of the assembly line is expanded, and thus, the occupied area increases. Under such circumstances, a storage conveyor has conventionally been used that utilizes a space above the workpiece conveyance path, with workpieces stored in a vertical direction (refer to Patent Document 1, for example). However, in the conventional storage conveyor, since a pair of endless belts (or endless chains) are arranged on both sides in a width direction of the conveyance path, the arrangement of (the gap between) the pair of endless belts must be changed depending on the workpieces. Thus, it is difficult to quickly respond to a change in workpieces. In addition, since the pair of endless belts always occupy the spaces on both sides of and above the workpiece conveyance path, the size of the storage conveyor becomes large and interferes with maintenance operation.
Patent Document 1: Japanese Patent Application Publication No. H03-106721